So far confirmed, as seen in the image and trailer, are Ryu, Wolverine, Iron Man, Morrigan, Hulk, and Chris Redfield.

Based on the silhouettes, and past history of the series, one can expect Spider-Man, Captain America, Cyclops, Magneto, Dr. Doom, Chun-Li, Mega Man, Strider, Zangief, and Felicia. Expect more to be announced. Until then, enjoy the trailer:

I actually suggested PWG doing some fan conclave like Chikara did, Super Street Fighter IV works totally or even Marvel vs. Capcom 2 as well, maybe have the conclave at BOLA or something but it won't work in Reseda honestly

Amaterasu from Okami and Thor were announced over the Comic Con weekend, although Marvel revealed them on their website a day before but the big news was the fact there's gonna be Street Fighter x Tekken (pronounced Street Fighter cross Tekken), its gonna be tag team and plays something like Street Fighter IV but Namco will make Tekken x Street Fighter, which will play something like Tekken 6 instead